let the user select a standard folder for all data produced

[pcav]

During analyses, many new files are often produced. They can confuse user, and it can be annoying reselectin a folder to save them every time. An option to save all files in the same default folder (e.g. where the project is placed) would be useful. This would be similar to the way GRASS behaves. Additionally, a default name could be suggested (based on the command being run, on the origin layer, or on a serial number), so the use could just run the analysis and click OK.